OpenSpecEngineering

Finds the takt time, the pace at which a process must finish units to keep up with customer demand. It also gives the pitch, the time to fill one container, and compares your actual cycle time with takt to show how many parallel stations or operators you need. Lean practitioners, production planners and supervisors use it when they draw a value stream map or set up a cell [1], [2].

Equations

T_takt = T_avail / D     pitch = T_takt · q

T_avail is the net available work time in the period: the shift length less breaks, lunch, meetings and planned cleanup. D is the customer demand in the same period. q is the pack-out quantity, the number of units in one container. Pitch is the interval at which a full container should leave the process, and so the interval at which to check whether the process is on schedule [1].

ratio = CT / T_takt     parallel resources = ⌈CT / T_takt⌉

CT is the actual cycle time per unit of one station or operator. A ratio above 1 means that one resource cannot keep up, and the count rounded up is the number of stations working side by side that can.

Limits and common mistakes

• Takt is set by demand, not by the process. Cycle time is what the process can do. Don’t mix them up [3].
• Don’t take unplanned downtime, changeovers or scrap out of the available time. Those are losses the process must absorb, so CT has to run below takt to cover them.
• Use the same period for time and demand: daily time with daily demand, weekly with weekly.
• A ratio just under 1 leaves no room for lost time. Lines often aim for a cycle time of 85–95 % of takt.
• Enter 0 for the pack-out quantity or the cycle time to skip that part.

Worked example

A plant runs two 8-hour shifts. Each loses 50 min to breaks and lunch, which leaves 430 min per shift, or 860 min a day. Customers order 520 units a day, packed 24 to a carton. The current station takes 2.5 min per unit. Can it keep up?

1. Enter Net Available Work Time per Period 860 and Customer Demand per Period 520.
2. Enter Pack-Out / Container Quantity 24 and Actual Cycle Time 2.5.
3. Press Solve. The Solution shows: Takt time: 1.65385 min/unit
   Takt time: 99.2308 sec/unit
   Pitch (takt × pack quantity): 39.6923 min
   Cycle time / takt time: 1.51163
   Parallel resources needed to meet takt: 2
   Status: Cycle time exceeds takt — demand not met

Check by hand. 860 / 520 = 1.654 min, about 99 s. A carton should leave every 24 × 1.654 = 39.7 min. One station at 2.5 min makes only 860 / 2.5 = 344 units a day. Two stations make 688, enough for 520.